Weakness and Dizziness Answers 391the day. (c)The third cranial nerve innervates many of the extraocular
muscles and the levator palpebrae. In addition, ciliary nerve fibers that
run along the third cranial nerve function to constrict the pupil. Damage
to the third cranial nerve often results in ptosis, mydriasis, and the classic
“down and out” eye. However, these symptoms do not wax and wane as
presented in this scenario. (d)Guillain-Barrésyndrome is an ascending
peripheralneuropathy classically presenting after a history of viral illness. It is
associatedwith loss of deep tendon reflexes and earlier symmetric, distal
weakness.
356.The answer is a.(Rosen, pp 1440-1442.)This patient’s BP of 215/118 mm
Hg needs to be lowered to 185/110 mm Hgto make her a good candidate
forthrombolytic therapy. Labetalolis the agent of choice in this case.
Fibrinolytic administration (b)at this level of hypertension carries a
risk of intracranial bleed. Daily aspirin (c)has been shown to reduce the
incidence of strokes. However, aspirin should not be administered within
24 hours of fibrinolytic use since it increases the risk of postthrombolytic
bleed. Antiseizure prophylaxis with phenytoin (d)is not indicated in ischemic
strokes although a small percentage of stroke patients will seize within the
first 24 hours. Hyperventilation and mannitol (e)are used for temporary
management of increased intracranial pressure owing to cerebral edema in
an ischemic stroke, which peaks at 72 to 96 hours. There is no role for
mannitol in acute stroke in a patient without signs of elevated intracranial
pressure.
357.The answer is c.(Rosen, p 2169.)Patients with initial flu-like symptoms
from the same householdwho were exposed to combustion products (ie,
from a home generator) are at risk for carbon monoxide (CO) poisoning.
CO binds to hemoglobin with greater affinity than oxygen and shifts the
oxygen-hemoglobin dissociation curve to the left, thus decreasing oxy-
gen release. Clinically, patients with mild CO toxicity present with flu-like
symptoms, nausea, and vomiting, which progresses to chest pain, dyspnea,
confusion, seizures, dysrhythmias, and coma. CO level can be obtained by
acarboxyhemoglobin levelfrom blood. CO poisoning is treated with oxygen
and, if severe, with hyperbaric oxygentherapy.
An important clue to the diagnosis is the development of similar symptoms
in the patient and her husband at the same time. While it is important to
consider ordering a WBC count (a),a head CT scan (b), and an LP (d)for
evaluation of the symptoms, think CO poisoning when there are multiple